Longitudinal assessment of occupational determinants of chlorpyrifos exposure in adolescent pesticide workers in Egypt

Catherine L. Callahan, Lamya A. Hamad, James R. Olson, Ahmed A. Ismail, Gaafar Abdel-Rasoul, Olfat Hendy, Diane S. Rohlman, Matthew R. Bonner

Research output: Contribution to journalArticlepeer-review

16 Scopus citations


Chlorpyrifos (CPF) is an organophosphourus insecticide applied to cotton fields by adolescents employed by the Egyptian Ministry of Agriculture. Urinary 3,5,6-trichloro-2-pyridinol (TCPy) is a biomarker of CPF exposure that has substantial variability among these applicators. In order to identify predictors of CPF exposure, we conducted a longitudinal study of 43 adolescent pesticide applicators in Egypt from April 2010 to January 2011 in Egypt. Urinary TCPy was quantified at 25 time-points, prior to, during, and following application. We used log-linear regression and a best subset selection approach to identify the exposure determinants that were most predictive of cumulative TCPy and participants’ highest TCPy values (peak exposure). Applicators had cumulative urinary TCPy levels ranging from 167 to 49,8208 μg/g creatinine. Total hours applying CPF (semi-partial r2 = 0.32), and total hours in the field applying other pesticides (semi-partial r2 = 0.08) were the strongest predictors of cumulative TCPy. Applicators had peak urinary TCPy levels ranging from 4 to 5715 μg/g creatinine. The amount of time applying pesticides prior to blood draw was the strongest predictor of peak TCPy (semi-partial r2 = 0.30). We also observed evidence that wearing clean clothes to work was associated with lower longitudinal TCPy. Our results suggest there is an opportunity for targeted interventions, particularly related to hygiene or implementation of personal protective equipment usage to reduce CPF exposure among adolescent pesticide workers.

Original languageEnglish (US)
Pages (from-to)1356-1362
Number of pages7
JournalInternational Journal of Hygiene and Environmental Health
Issue number8
StatePublished - Nov 2017


  • Biomonitoring
  • Chlorpyrifos
  • Occupational exposure
  • Organophosphates
  • Pesticide applicators

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health


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